1. Field of the Invention
The present invention relates to a rail vehicle for providing work relating to the track, preferably self-propelled, comprising an excavator including a narrow gripper and disposed near an end of the rail vehicle.
2. Brief Description of the Background of the Invention Including Prior Art
Rail vehicles for providing work relating to the track are known and such a rail vehicle is for example disclosed in German Democratic Republic Pat. No. 61,805. Such machines allow to perform different kinds of work at the rail and such rail vehicles are frequently called multi-purpose vehicles. Such machines are frequently self-propelled by their own drive units. For this purpose in most cases a cabin is provided disposed at the side of the rail vehicle opposite to the location of the excavator.
In order to perform measurements at the track body or at the rail bed additional measurement devices are required. The above cited GDR Patent is not equipped for the investigation of soil mechanics. In the practical performance of such investigations there was cleared out the interspace between two cross-ties at predetermined distances along the track and then several days later inspected by eye, then again filled in, packed and tamped. Thus the investigated rail section could not be used for rail traffic for several days. In case the track was used, then the surrounding material already had partially filled the dug out hole again.
For measuring and checking of the soil mechanics in the area of the formation level a pressure piston method is known. For this purpose a cylinder with a diameter of about 5 cm is pressed into the ground to be investigated with a constant speed and the pressure to do this is determined. In order for the ground around the pressure piston not to well up lead rings or half lead rings are placed around the pressure piston. These are to simulate the pressure situations at the same time, which prevail usually in the region of the investigated bed in the presence of an upper structure.
It is the purpose of the investigation of soil mechanics to determine early damages in the region of the formation level, before these can become effective for the rail section proper. On the other hand soil mechanics are also investigated in order to avoid unnecessary expenses of work to be performed based on an underestimate of the ground material.
Usually, there is a ballast bed disposed below the cross-ties of a railroad rail and the ballast bed can have varying thickness, and in typical cases the ballast bed from broken stones reaches to 50 cm below the upper edge of the rail. The lower boundary of this ballast bed is designated as formation level or subgrade. The soil mechanics investigated here refer to the lower disposed region, which is called here formation level region.
Upon traffic passing the ballast bed having a certain amount of elasticity transfers the load of the train to the formation level. Under the load of the train and in particular under the load of the axles of the locomotive a rail is pressed down from its rest position frequently by several centimeters. Similarly the elastic ballast bed is pressed together. With the load removal the ballast bed expands again and the rail takes on again its usual rest position. These load changes repeat upon passing of a train over a point considered many times and the formation level is loaded with a pulsating pressure. In case the formation level is wet such as for example caused by inadequate drainage, then by way of the continuous pumping motions the mud moves upward in the ballast bed into the region of the rails. This changes the physical conditions of the upper structure drastically, and the upper structure is not any longer elastic and disturbances of the traffic operation occur.
An insufficient capability of support of the under structure of railroad tracks results primarily in the following damages:
continuous occurrance of level and directional errors of the rail;
increased maintenance requirements;
areas with speed limitations; and
premature wear of upper structure and of the rail vehicles.
The drainage of the formation level is one of the most important preconditions for the stability of the track. The depositing of residues upon machine cleaning at the foot of the bed near the edge path and filled, soiled, grown in or too flat rail ditches interfere with the flow off of the rain water on the formation level and in the rail ditch or side drain. This results in the water penetrating the subgrade and slowly softening the subgrade.
Reliable measurement procedures are known for determining the state of the formation level. However, since the investigation of the soil mechanics is in particular necessary and of prime importance with high traffic lines, where a temporary placing out of service would result in drastic timetable curtailments the necessary steps have frequently not been performed. For safety reasons and in order to increase the speed of the trains passing and the weight on the axles such investigations of the formation level are indispensable. However, no suitable measuring devices are presently available for this purpose. The performance of the known method is much too slow and too time consuming and labor intensive and the practical performance does not always lead to reliable values as in particular measuring errors cannot always be excluded. For safety purposes frequently a decision is made for precautionary improvements of the formation level, especially for exchange work. However these amount to more than $100,000 per kilometer of the track.